1. Field of the Invention
The present invention relates to ceiling fans and more specifically, to a motor control circuit assembly for use in a ceiling fan to control the operation of the brushless motor.
2. Description of the Related Art
In a brushless motor type ceiling fan, a Hall effect sensor used to detect the change of magnetic pole position of the rotor, and a field effect transistor is necessary for output drive. The voltage of the field effect transistor is relatively low, and therefore the field effect transistor is not in “full conduction” for full power mode, i.e., the power factor is at a low level, wasting much electricity and releasing much heat.
Further, PWM (Pulse-width modulation) is commonly used in the control of the speed of a brushless motor in that involves the modulation of its duty cycle to control the amount of power sent to the load. It is used to control the supply of electrical power to the brushless motor, thereby controlling the speed of the brushless motor. However, this control method cannot eliminate vibration of the fan blade during rotation, resulting in a high noise level.